camera modules to angles perpendicular to the scanner faces.
lso, the construction of a
scanner would be complicated by including camera modules into the structure.
The second option is to build a separate enclosure for the camera modules and attach this to the scanner. This would increase the overall size of the scanner and have a visual im- pact. The orientations of the modules would not be limited as in the first scenario. For the prototype constructed in this research the second option was chosen. However, in order to reduce the overall size for a commercial system, building the tracker into the scanner body would be a better option.
The maximum size of the tracker if it were built into an enclosure and attached to the scan- ner should be small enough so that the look and feel of the system is not compromised. The FastSC N Scorpion(TM)  has a length of approximately 36 cm and a width of ap- proximately 13 cm. By placing the hub enclosure on the top of the scanner and by keeping the enclosure diameter within the width of the scanner, the size of the scanner is not in- creased significantly. Based on these measurements, a sphere of diameter 10 cm would be a suitable basis for the tracker.
The system must be light enough for ease of use of the scanner. If the tracker is too heavy then this could limit how long an operator could comfortably use the scanner. Govern- ment agencies world-wide have guidelines on the maximum weight employees should lift. However, data could not be found on acceptable weights for sustained lifting such as could be encountered by an operator using the scanner. maximum weight of 500 g for the tracker was chosen based on the weight of common 500 g mineral water bottles. These are of a weight that can easily be lifted using one arm (even in a state of dehydration). It is
a s s u m e d t h a t t h e w e i g h t o f t h e s c a n n e r c a n b e l i f t e d e a s i l y b y o n e o f t h e o p e r a t o r ’ s a r m and the other arm could support the extra weight of the optical tracker. The scanner would therefore be held in both hands. s
The system is intended for use indoors and should work in conditions found in a typical office environment. It is assumed an office environment would not fall below 5 ◦C or rise higher than 35 ◦C.
The system is intended to be used in a tethered environment so power consumption is not a major issue from an energy conservation point of view. Therefore, power consumption is